Rights concerns have delayed the issuance of the United States Pioneers of Graphic Design commemorative stamps originally planned for April.

Licensing the rights for the stamp designs is “taking longer than anticipated,” said Susan McGowan, U.S. Postal Service stamp services executive director, in an interview with Linn’s Stamp News.

The set was originally planned for April 25 in conjunction with an event in New York City celebrating the 100th anniversary of the American Institute of Graphic Arts.

The pane is now scheduled for an October release, but McGowan indicated that even that date is tentative.

Journalists were shown a preliminary design for the stamp pane in October 2013 that included art by 12 designers. That preliminary layout resembled the Pioneers of American Industrial Design pane from 2011 (Scott 4546), but it’s possible that the layout for the new Pioneers of Graphic Design set could change.